1. Field of the Invention
The present invention relates to a liquid ejection apparatus, such as an inhaler capable of enabling a user to inhale liquid, typically liquid containing physiologically active substance, such as medicament or drug, as droplets.
2. Description of the Related Background Art
In recent years, as medical and other sciences advance, average life expectancy increases and an aging society is coming nearer. At the same time, people's dietary habits and living environment are changing, and environmental pollution becomes more serious. Further, new illnesses and infectious diseases due to viruses and bacteria are discovered, and people's uneasiness for health grows stronger. Particularly, in developed countries, the number of individuals suffering from lifestyle-related illnesses, such as diabetes and high blood pressure, increases considerably.
On the other hand, the number of medical institutions is not increasing so fast as can deal with increase in the number of people suffering from the above illnesses. There exist even such areas as cannot provide medical institutions at which each individual can see a doctor regularly. Therefore, appropriate future measures including policy are desired strongly.
Exemplified cases will be described. Among patients of diabetes the number of which is presently increasing, patients of I-type diabetes, i.e., insulin dependent diabetes, have pancreas incapable of secreting insulin. Hence, those patients should receive regular administration of insulin. Presently, dosing of insulin is executed by hypodermic injection. Physical and mental burdens of users are accordingly seriously heavy.
To lighten those burdens of users, there has been developed a pen-type syringe with a thin needle and with little attendant pain. Patients of I-type diabetes mostly live ordinary lives similar to those of healthy people, with the exception that the patients should receive regular administration of insulin. Therefore, even in the case of the pen-type syringe, patients naturally undergo mental hardship of injection before the presence of other people. It is thus difficult for those patients to do self-administration of insulin at appropriate times. Consequently, there is a possibility of inappropriate treatment of patients using such a method.
Further, treatment of users capable of making use of information database, such as an electronic patient's case record, is being coming true by means of a medicament inhaler for dosing a user with medicament through inhalation. Such a medicament inhaler is equipped with a memory unit for storing information about an individual, such as data of user's case record and data of user's prescription, and an ejecting unit for ejecting liquid medicament as minute droplets. The medicament inhaler further includes an ejection control unit for controlling the ejecting unit according to a user's inhalation profile to eject the medicament so that the user can inhale the medicament in accordance with the information of the prescription. In this connection, see PCT International Publication Nos. WO 95/01137, and WO 02/04043.
With such a medicament inhaler, the number of kinds of medicaments or medicines capable of being dosed is increasing. In such a situation, countermeasures for preventing an erroneous loading or installation of a medicament container or tank are required. For those purposes, there has been proposed such an inhaler that includes a tank with a code for distinguishing or discriminating the kind of medicament stored therein, an ejecting head for ejecting liquid medicament supplied from the tank as droplets, and an ejection permitting unit. The ejecting permitting unit reads the above code, and puts the ejecting unit in an operable condition only when the medicament stored in the tank is compared with, and found to coincide with medicament described in information of a prescription stored in the memory unit. In this connection, see Japanese Patent Application Laid-open No. 2002-165882.
Patients or users of medicament inhalers are often elderly people who suffer from plural diseases and troubles. Those users frequently must inhale a plurality of kinds of medicaments. In such a case, appropriate administration parts of a body of the user can vary according to the kind of medicament. A most important factor for determining the medicament dosage part of a body is the size of a liquid medicament droplet being ejected from the medicament inhaler. For example, the diameter of the droplet is said to be preferably about three (3) microns for absorption via pulmonary route, and if the diameter is larger than that, droplets are liable to be stopped at bronchia and so forth. Conversely, in order to cause the droplets to act at bronchia, the diameter of the droplet is preferably about five (5) microns. If the diameter of the droplet is less than one (1) micron, its value is too small. The droplets are surely exhausted from the body along with user's exhalation. In other words, there are cases where medicament is subjected to topical application as in bronchial diseases, and where medicament is administered to the entire body through pulmonary alveoli and blood flow as in diabetes using insulin, and a suitable diameter of liquid medicament droplet varies according to cases.
Further, there is a variation between individuals. For example, a location of the body where drug reaches varies between individuals even when the diameter of liquid medicament droplet is the same. Appropriate diameters of medicament droplets for achieving their medical effects can thus vary among individual users.
Generally, it is necessary to change the diameter of a nozzle disposed at an ejecting end portion of a medicament ejection cartridge in order to adjust the above-discussed diameter of the liquid medicament droplet. Such necessity, however, causes occurrence of innumerable combinations of liquid medicament cartridge tanks and medicament ejection cartridges. This situation imposes annoying or troublesome management and carefulness on users, and brings forth a possibility of impediment of appropriate inhalation. These matters are critical for users.
It is hence preferable to provide a liquid medicament container or tank and a medicament ejection head separately, considering the fact that there are cases where various kinds of medicaments need to be ejected as droplets with appropriate diameters, where an individual patient should inhale plural kinds of liquid medicaments, and where a plurality of users employ a common inhaler. Such separate preparation increases the number of combinations, and allows appropriate combinations to be used in accordance with various cases.
In the above situation, however, plural liquid medicament cartridge tanks and plural ejection cartridges must be prepared, leading to not only annoying or troublesome management, but also impediment of appropriate inhalation caused by selection of an erroneous combination, as discussed above. With the inhaler of the above-mentioned Japanese Patent Application Laid-open No. 2002-165882 using a tank with a code for distinguishing plural kinds of medicaments from one another, it is possible to prevent an erroneous loading of the liquid medicament tank, but difficult to cope with the above-discussed problems.